1. Field of Invention
This invention relates to dual load highway trailers, and more particularly to trailers having an upper deck which is lowerable to allow easy loading from ground level, movable axles to facilitate loading, and biasing means to facilitate movement of the upper deck.
2. Description of the Prior Art
The prior art discloses a variety of highway trailers intended to be pulled behind a motor vehicle and adapted to transport two or more loads on two decks, arranged vertically, end-to-end, and otherwise. Various means are employed to facilitate loading and unloading.
U.S. Pat. No. 4,068,772 discloses a double deck trailer in which the upper deck is collapsible on pivoted legs to facilitate loading. The rearmost pair of pivoted legs in this disclosure is slanted outward to bias the upper deck toward collapse.
U.S. Pat. No. 4,221,420 discloses a double deck trailer especially adapted to hauling a car on the lower deck and a boat on the upper deck. The upper deck is moved up and down by a pair of scissors arms located on either side of the load platforms. In this disclosure, a hydraulic ram actuates the scissors arms.
U.S. Pat. No. 4,406,477 discloses a double deck highway trailer especially adapted to transporting a car on the lower platform and a boat on the upper platform. The upper platform is lowered vertically by pulley cables on vertical, rigid stanchions.
U.S. Pat. No. 4,469,346 discloses a double deck highway trailer assembled by attaching together two independent trailers in piggyback fashion. The upper trailer is supported by pivoted arms and is raised into position by a winch. In this disclosure the rear pivoted arms are slanted rearward to facilitate collapse.
U.S. Pat. No. 4,560,316 discloses a trailer especially adapted for simultaneously carrying a motor vehicle and a boat. The boat is carried in a horizontal position. A wheel carriage assembly allows movement of the road wheels in the longitudinal direction to facilitate balancing and loading of the trailer.
U.S. Pat. No. 4,589,814 discloses a double deck highway trailer especially adapted to carry a motor vehicle on the first deck and a boat on the second deck. The upper deck is supported on four pivoted arms which allow the upper deck to be lowered. Additionally, the upper and lower decks together can by pivoted about a transverse axis of the main frame to allow both decks to come to ground level.
U.S. Pat. No. 4,597,585 discloses a tandem trailer assembly of telescoped design to achieve a reduced overall vehicle length.
The principal limitation of the prior art is that none of the inventions disclosed provide positive means for biasing the pivoting arms supporting the upper load surfaces both toward collapse when in the fully extended position and toward extension when in the fully collapsed position. Additionally, none combines the collapsible double decker design with means for longitudinally moving the road wheels. Accordingly, it is the object of this invention to provide a double deck highway trailer with upper platform movable to a lowered position with pivoted arms which are biased both toward extension when lowered and toward collapse when in a raised position.
A second object is to provide a means for longitudinally repositioning the road wheels to facilitate loading and load balancing.